Recently, news reports were briefly dominated by the doomsday predictions of Harold Camping, an American pastor claiming he had discerned from biblical clues that the world would end at 6PM on Saturday May 21. Camping had previously warned that the rapture would occur in 1994. Despite his zero-for-two record, Camping isn't giving up. He's already moved on to a new prediction, claiming the world will actually end in October.

Attention-seeking religious leaders don't have a monopoly on false doomsday predictions. There is at least one prominent secular political movement that also has a long track record of apocalyptic visions that have failed to materialize. That movement is radical environmentalism. With apocalyptic predictions in mind, it's worthwhile to review radical environmentalism's track record of incorrect catastrophic predictions.

As David Frum describes in his indispensible book, How We Got Here, doomsday prediction became a staple of far-left environmentalist rhetoric during the 1970s. One prominent strain of apocalyptic prophesy during that decade was the prediction of disastrous impacts from overpopulation. The most famous spokesman for this theory was Paul Ehrlich. In his bestseller The Population Bomb, he warned that global catastrophe was imminent and that the world would soon endure a famine in which hundreds of millions would starve. Ehrlich offered a few helpful suggestions on how slightly to reduce the damage, for example, recommending pets be killed to conserve resources.

Of course, forty years later, the economic and societal collapse predicted by Ehrlich hasn't happened. Instead, population has continued to increase while average living standards have gone up almost everywhere in the world.

The overpopulation scare was not the only false catastrophe narrative promoted by environmentalists during the 1970s. Long before we became concerned with global warming, the great source of anxiety was global cooling. There was fear that the burning of fossil fuels was raising the concentration of polluting particles in the atmosphere, which would reduce solar heat reaching the earth, leading to a new ice age. One major study published in 1974 warned there would "almost certainly" be major crop failures as a result of global cooling by 1980. Stories about the threat of global cooling were featured on the front page of The New York Times and the cover of Time magazine.

Global cooling fears subsided when the world stopped cooling, and started to warm up. This brings us to the apocalyptic warnings surrounding global warming we hear so frequently today. Doomsday rhetoric about this crisis-of-the-moment has been every bit as lurid as that which predicted catastrophic global cooling and mass starvation.

For example, Australian environmentalist Tim Flannery writes in his popular book, The Weather Makers, that unless greenhouse gas emissions are curbed dramatically, a warming climate will destabilize human civilization and create "a protracted Dark Ages far more mordant than any that has gone before." United Nations Secretary-General Ban Ki-moon warns that the world faces a stark choice between "strong action on climate change" and "oblivion." Like other apocalyptic environmentalists before them, Flannery and Ki-moon claim that unless we do as they say, utter catastrophe looms. The rhetoric has stayed the same, but the precise nature of the supposed environmental disaster has changed.

Naturally, the fact that the radical environmentalists' earlier doomsday predictions haven't materialized does not mean we should dismiss concern over global warming or ignore environmental risks. We should continue to assess and respond to those risks rationally. However, we should also treat apocalyptic prophesies from the deep green movement with healthy scepticism.

There is an element of the environmentalist movement that has been gripped for forty years by the conviction that the activities of advanced, industrialized economies will lead to an apocalyptic environmental collapse one way or another. This faction has worked backwards from this assumption, always seeking causes that will trigger the cataclysm they believe is an inevitable consequence of the high levels of economic production and consumption of a capitalist economy. Although we should take environmental risks seriously, we should also recognize the environmentalist movement's track record of overhyping those risks, and consider that record as they continue to insist that civilization will collapse if we refuse to enact their policy agenda.

Given his track record, it's no wonder fewer people are taking Camping's newest rapture timetable seriously. Radical environmentalists have also built a record of wrongly predicting massive cataclysms, and we should be hesitant before enacting policies that entail enormous economic costs in reaction to their latest set of doomsday predictions.